FIELD OF THE INVENTION
The invention relates to semiconductor manufacture and, more particularly, to a method for producing bridged, doped zones.
A problem that repeatedly arises in integrated semiconductor products is that conductor tracks have to be routed via a doped zone in the semiconductor. DMOS transistors, for example, frequently have an annular deep diffusion zone which functions as a drain terminal and completely surrounds the source and/or gate regions of the DMOS transistor. In order, then, to enable driving the DMOS transistor, it is necessary to route a conductive connection via the annular deep diffusion zone to the gate electrodes. In this case, it is imperative for the function of the DMOS transistor that the conductive connection and the deep diffusion zone be completely insulated from one another. The insulation is usually provided by a silicon oxide layer of sufficient thickness.
For process engineering reasons, however, it is not always possible in the conventional processes to provide a silicon oxide layer which has a sufficient thickness for the proper insulation. If one nevertheless wished to produce a conductive connection across the doped zone in such a situation, one would have to move to a higher metalization plane, since this higher metalization plane is separated from the doped zone by at least one further insulation layer. One of the negative consequence of this move to a higher metalization plane, however, is that additional vias to the higher metalization plane have to be provided.